[{"key":1},{"key":2,"clicks":{"2022-02-03":30,"2022-02-02":50,"2022-02-01":45,"2022-01-31":40,"2022-01-30":40,"2022-01-29":50,"2022-01-28":55,"2022-01-27":50,"2022-01-26":40,"2022-01-25":30,"2022-01-24":35,"2022-01-23":33,"2022-01-22":32,"2022-01-21":30}}]

db.collection.aggregate([{$project:{"c":{"$objectToArray":"$clicks"}}},{"$project":{"clicks":{"$sum":"$c.v"}}}])